1. Field of the Invention
The present invention relates to a method and apparatus for combining a plurality of character patterns to produce a character pattern of a new typeface.
2. Description of the Related Art
Character patterns are widely used in apparatuses which display and/or print characters. Those apparatuses have character patterns stored therein, generate character patterns corresponding to character codes and display or print the patterns. The character patterns are typically bit-mapped when stored. For Kanji characters or the like which include many characters, the bit-mapping of the individual character patterns increases the memory capacity, so that a method of storing characters in an outline (contour line) format becomes popular.
This outline system is advantageous over the bit-mapping system in data compression.
There is a demand for an increased number of typefaces for Kanji characters or the like. It takes time and efforts to design new typefaces for a vast amount of characters like Kanji characters to meet the demand. It is therefore desirable to create new typefaces without actual designing.
FIGS. 23A and 23B are explanatory diagrams of interpolation and combining, and FIG. 24 is an explanatory diagram of an operation to interpolate characters. To efficiently develop character typefaces, there is a scheme to combine typefaces ("blend" is used in a broad sense). This combination includes "interpolation" and "combination" (in a narrow sense). FIG. 23A exemplifies the interpolation of a typeface to produce an intermediate Mincho character having an intermediate weight from a light Mincho character A and a bold Mincho character B. FIG. 23B shows an example of combining (in a narrow sense) typefaces to produce a new typeface, which is in-between Mincho and Gothic characters, from a Mincho character A and a Gothic character B.
As shown in FIG. 24, the light Mincho character A and bold Mincho character B both have, for example, five contour lines (patterns) 1 to 5 for typeface interpolation. The corresponding contour lines for both Mincho characters are detected, and corresponding contour points on the corresponding contour lines are found. Then, middle values of the corresponding contour points are generated as new contour points. For the combination of typefaces, likewise, corresponding contour lines for the Mincho and Gothic characters are detected, and corresponding contour points on the corresponding contour lines are found. Then, middle values of the corresponding contour points are generated as new contour points.
FIG. 25 is an explanatory diagram of prior art. One known way of finding such corresponding contour lines is to arrange individual contour lines in the same order between different typefaces and to arrange contour points on each contour line in the same order between different typefaces as shown in FIG. 25 (see Japanese Unexamined Patent Publication No. 272460/1989, for example). Another method is to arrange contour lines in a different order and recognize the patterns of the contour lines to search for corresponding contour lines.
The prior art, however, has some shortcomings. First, prearranging contour line data in the same order between typefaces is restrictive in font development and increases the number of steps in the font development. Secondly, the arrangement of contour points requires that individual typefaces should have the same number of contour lines laid out at the same positions previously. This increases the number of steps in the font development and the amount of font data.
The scheme that uses pattern recognition to associate contour lines and contour points for one typeface with those of another typeface involves a complicated pattern recognition algorithm which takes time in processing data. If a pattern to be recognized is complex, erroneous recognition may occur, resulting in frequency failure of interpolation and combination. Further, some characters have different numbers of contour lines for light and bold Mincho characters. For instance, a Kanji character "Ai" shown in FIG. 26 has differenct numbers of contour lines for its light Mincho character A and its bold Mincho character B. Furthermore, the first contour line of the Mincho character A has a different shape and size from those of the Mincho character B. As there are many such characters that are designed as to have separate contour lines for their light Mincho characters A but have overlapping contour lines for their bold Mincho characters B, those characters cannot automatically be generated by associating their contour lines of one typeface with those of another typeface or by pattern recognition.